It really depends on the artist. I actually think most good artists who draw well are (today's, not 1970s and 1980s) shojo manga artists. Shojo manga are usually prettier. The clothes and backgrounds are better and are with more details. I wish more seinen and shonen manga are drawn like the shojo styles I like. Some of the josei and shonen artists also have unique, pretty yet different from shojo styles, which I also like a lot (those types are my personal favourite since many run-of-the-mill shojo manga's art styles don't have much personality and are not prettier).

Not all. Some are actually good. Like Fullmoon wo sagashite and Shinshi Doumei Cross. =/ Also ION.

definitely. Arina Tanemura draws REALLY good, so I always like to read stuff by her
and Matsuri Hino. so it depends on the person who draws it, in my opinion.
however, i don't really like the art in furuba (their eyes are freaky!!!) but i still really like it, though.

The big eyes and other things all belong to the shoujo style of storytelling. Shoujo is all about moods, emotion, and relationships, so the eyes are used to convey many emotional messages. Along time ago I meet a female shoujo manga creator at a anime convention, and I asked her about all the super fancy clothes and hair styles in shoujo manga. She told me that in a society where the kids have many rules about how to wear their uniforms and hair at school she creates her characters, their clothes, and the hair styles based on how she thought her fans wanted to see themselves as, not as how they actually have to dress like and act like in real life. So, shoujo manga is a fantasy world where the girls are freer to express themselves then in the real world were they live.

I thought big eyes belonged to the "moe" category in male-oriented manga or in "bishojo" games. Characters in those usually have FAR larger eyes than most characters in (today's) shojo manga. I guess the moe and "bishojo" game drawing styles are borrowed from older shojo manga but with some modifications (like the girls look less skinny with rounder face and the other stuff you all know).

I think it depends - I love dark Shoujo art like in Prince of Monster - and Alichino is very well done. Big eyes small mouth has everything to do with stylization and nothing to do with how well something is drawn. You have to take a look at a few Grey's Anatomies (not the show >_>) in order to figure out whether somone's art is just really stylized or they don't know what they're doing. For instance - a chibi wouldn't be considered bad art - just incredibly stylized - but if you knew anatomy (or had seen a lot of chibis) you would know a bad chibi when you saw one.